Tolerance gauge



Feb. 24, 1931. H. v. TRNEBOHM l 1,793,763

TOLERANCE GAUGE Filed March 51, 1928 Patented Feb. 24, 1931 um'rso STATES PATENT OFFICE BIIDING 'VALDEMIAB TBNEBOHI, 0F' GOTTENIBORG, SWEDEN, ASSIGNOR T0 .AKTIE- BOLAGET SVENSKA KULLAGEBFABRIXEN, F GOTTENBORG, SWEDEN, A. CORPORA- TION 0F SWEDEN TOLERANCE GAUGE Application llled Iarch 31, 1828, Serial lo. 266,263, and in Sweden July 25, 1927.

For gauging the size of holes determined by tolerances, so-called tolerance gauges are generally used. `These gauges havebeen of various constructions, for instance round B' plug gauges, flat tolerance gauges or end gauges, provided with two gauging organs, the minimum gauge and the maximum gauge, most generally united by means of a handle or the like. If the hole is to be considered as approved, it must have its dimensions between the values represented by the two gauging organs, one of them--the minlmum gauge-must be of such a dimension as to easily enter the hole, whereas the other-the ,l5 maximum gauge-must not enter the hole.

If the first condition, viz. the minimum condition, vis not fulfilled, the hole is considered too small, whereas2 if the other condition, the maximum condition, is not fulfilled, and

2 the maximum gauge can enter, the hole is considered too large.

The tolerance gauge lmown as round tolerance gauge is probably the most common. By means of such a tolerance gauge it is,

however, only possible to check the magnitude of the-inscribed circle o the hole. A possibly existing ovality cannot be ascertained, and thus it is not possible with such a gauge to find out whether the maximum diameter of the hole lwill be less than the maximum diameter determined for it.

With the other unusual constructions of tolerance gauges, known as at tolerance gauges or end gauges, it is, on the otherhand,

u possible to check the diameter dimensions .existing in the hole. Such gauges, however, cannot be used for checking the inscribed circle of the hole.

Quite recently a new-construction of tolerance gauges has come into use. This consists of round minimum gauge and in addition to this a liat gauge or still better an end gauge as maximumv gauge. `By means of such a tolerance gauge it is possible to check not only whether the inscribed circle of the hole is larger than the determined minimum value, but also whether the maximum diameter of the hole is smaller than the maximum limit value determined. This control can4 be considered satisfactory as being decisive for 4the fitting qualities of the hole.

With my present invention handling is essentially facilitated, inasmuch as the checking of the maximum dimension can take place without the necessity'of removing the minil other that the gauge takes u different angular ositions in relation to t e center line of the ole.

The drawings accompanying this application illustrate a practicable embodiment of the invention wherein- Figure 1 shows aside elevationo my improved gauge applied to the bore of a workpiece, the gauge being in the position indicating that the bore of the work-piece is between the prescribed tolerances.

Fi 2 is a view similar to Figure 1, the han e being shown broken away. In this view the bore ofthe work-piece is repre sented as being smaller than the minimum tolerance.

Fig; 3 is a view similar to Fig. 2 indicating that the bore is larger than the maximum tolerance.

Fig. 4 is a view looking at the head of the gauge, so that with the constructions shown in the previous iures this might be called looking downwar y.

Fi 5 is an end view of the gauge from the leftand side of Figure 1, and

Figs. 6 and 7 represent a modified form of the device to be described at the proper place.

The head 104 of the gauge is 'represented as beingan equatorial portion of a spherical body having a diameter which is equal to the minimum dimension of the work-piece, i. e. assuming that the bore 11 of the workpiece 12 is to be of a diameter not less than a prescribed measurement, the diameter 13 of the spherical surface of the head 10 is such that the head may enter the bore with a nice working lit. ln Fig. 2 the bore 110 of thework-piece 120 is of a diameter smaller than the spherical diameter 13 of the head 10. Consequently, the gauge cannot enter the work-piece.

For gauging projection or protuberance is formed on or carried by the head 10. ln Figs. 1 to 5 inelusive, this protuberance is in the form of a boss 14 which, in practice, will be a thin metal body of generallycircular outline secured to the body of the sphere by some electrolytic process. The diameter 15 taken from the face of the boss 14 to a point directly opposite, represents a value slightly in excess of the maximum dimenslon, and if when the gauge is inserted in the work-piece it can rock, referably'by means of its handle, so that the oss 14 clears the diameter of the workieee, in the illustration, the diameter 111 o the work-piece 121 of Fig. 3, the bore is assumed to be too large. f

lt must be understood that in most tolerance y'gauging where this improved device Willibe used, the diderence between the minimum and the maximum dimensions is much less than can conveniently be represented in a pen and ink drawing ofthe character of a Patent Oiice drawing which has to be made with a view to its permanency and the manner in which reproduction will be made. The principle, however, is the same whether the tolerance is represented as either great or small.

It will be noted in connection with the boss 14 that the side toward the center of the body 10 is formed with a sharp edge 16. rlhis edge may be readily kept in shape and reformed by lapping off the rear face from time to time. only adjustment or attention the gauge will require as long as a suliicient mass of the boss remains, its outer surface being substantially spherical and struck from the center 17 of the body 10.

ln using the gauge the operator will seek to enter it into the work-piece as in Fig. 2 in such a position that the boss 14 clears theA bore of the work-piece. He then will move the handle in an angular direction, see Fig. 1, generally holding it so that its own weight will cause the spherical body 10 to rock within the bore, which, if such bore 11 comes within the' prescribed tolerances, will cause the Sharpe edge 16 ofthe boss 14 to bite into the bore, which will stop the rocking movement. The operator will, in causing the reverse rocking of the spherical body andthe movement of the sharp edge away from the bore, feel its release and then the free and easy movement of the spherical body.

When the difference in diameter between the maximum diameter a.

rllhis will practically be the l weaves the sphericalbody 10 and the boss 14 is very slight, the spherical body, except for this boss, will have a nice, free, working `movement Within the bore if this is of the proper size and is round and is cylindrical, s0 that the Operator may readily inspect the work-piece not only to see that it has at least the minimum diameter, but that the bore is round in cross section vfrom end to end, and that it is of approximately the same diameter from end to end. And he may from place to place during this inspection, by merely rocking the gauge, ascertain that the maximum diameter has not been exceeded.

In some instances it may be found referable to form the boss or the surface or the maximum gauge in an insert. This is illustrated in Fig. 7 in which the spherical head 2() of the gauge is shown provided with an obliquely disposed hole 21 in which is inserted a pin 22 having one or both of its'head ends 23, 24 lextending beyond the spherical contour 25 of the head of the member 20. This pin or insert will preferably be .removable so that it may be repaired or replaced as occasion may require. Another advantage of the ready removability of the boss is the facility with which the sphere may be polished.

It is, of course, obvious that changes may be made within the scope of the claims without departing from the spirit of my invention.

Having described my invention, l claim and desire to secure by Letters Patent:

1. ln a tolerance gauge, a body portion comprising the equatorial zone of a sphere, the diameter of a great circle thereofconstitut-ing the minimum gauge, and a boss imposed uplon Such spherical surface and having a sp erical outer surface concentric with such body portion, such boss being wholly disposed upon one side of the great circle delining the equator of the spherical body and formed with a sharp edge on its side toward such great circle. 0

2. A tolerance lug gauge, com risin a bod portion having a sphericall) forged sur ace the diameter of a great circle of which constitutes the minimum gauge, and a part having a face protruding beyond such spherical surface and constituting in conjunction with the diametrically opposed portion of the spherical surface the maximum gauge, such protruding portion having a spherically formed gauging surface.

3. A tolerance gauge, comprising a body portion in the form of an equatorial zone of a sphere the diameter of a great circle of which constitutes' the minimum gauge, and a boss imposed upon the spherical surface thereof and having a spherical outer face concentric with the sphere center of such bodv portion.

4. In a tolerance gauge, a body portion comprising the equatorial zone of a sphere, the diameter of a great circle thereof constituting the minimum gauge, and a boss imposed upon such spherical surface and having a spherical outer surface concentric with such body portion, such boss being wholly' disposed upon one side of the great circle defining the equator of the spherical body.

5. A tolerance plug gauge comprising a handle, a body portion having a spherically formed surface the diameter of a great circle 0f which constitutes the minimum gauge and a part having a face protruding beyond such l. spherical surface and constituting in conof March 1928. Y

H. V. TORNEBOHM. 

